Polyolefin elastomers (POEs) are widely used in automotive, photovoltaic film, and home appliance industries. Compared to the classic copolymerization of ethylene and α-olefin (mainly 1-butene and 1-octene), branched polyethylene (PE) bearing similar elasticity as that of the POE is getting more attention recently. A number of cationic nickel catalyst systems were established, and good to excellent elasticity was achieved. In this work, we developed a series of anilinotropone nickel complexes bearing a hemilabile ethereal group and efficiently polymerized ethylene to produce branched PE. Tensile property study revealed that PE synthesized from the Ni2 (PENi2) catalyst displayed a stress-at-break value of 7.7 MPa and a strain-at-break value of 1870%. Interestingly, the strain recovery (SR) of PENi2 (79%) is higher than that of POEs 8150 (67%) and 7447 (67%). Quantitative 13C NMR studies suggest that PENi2 has mainly a methyl branch and a higher total branching density (88/1000) than POEs 8150 (46/1000) and 7447 (76/1000).
Hu et al. (Sun,) studied this question.